Seismic Behavior of Concrete Bridge Piers Reinforced with Steel or GFRP Bars

Abstract

This paper evaluates the seismic behavior of eight one-third-scale concrete bridge piers reinforced with various configurations of steel or glass fiber-reinforced polymer (GFRP) bars. Each specimen was tested under a constant axial gravity load, combined with reversed quasistatic cyclic lateral loading. The behavior of the piers was assessed and compared in terms of strength, stiffness, deformability, energy dissipation, and damage. The results indicate that well-detailed hybrid configurations with steel longitudinal bars and GFRP spirals offer a ductile seismic response with reduced postpeak strength degradation. The GFRP spirals were effective in confining the concrete core and restraining longitudinal bar buckling. Piers reinforced with GFRP longitudinal and transverse bars exhibit a stable and deformable seismic response with little residual displacement or strength degradation. However, this behavior was accompanied by a reduction in effective stiffness exceeding 40% and approximately half the hysteretic energy dissipation at an equivalent drift level. All piers reinforced with GFRP bars or spirals exceeded lateral drift requirements set by North American codes. © 2023 American Society of Civil Engineers.